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Indoor environment and health
Plants for clean air
Introduction
In 1989 after nearly 20 years research NASA published that the superior
air purification was carried out by a system consisting of plants and
soil. The root zone system BioVentic is an air treatment system based
on light soil filter with vegetation / root zone. Contaminated air is
pressed through the filter by a ventilator. Energy consumption is 38
watt/h. Installation has been set up in Denmark, Sweden, Netherlands,
USA and since 2007 in Greenland. This study has been made with a view
to objectifying root zones possible cleaning efficiency in slightly
different setups measuring selected parameters which normally are used
when examining indoor climate. While NASA has been working with tests
under strictly controlled conditions, this present study was on
practical plants in operation. The study has shown that especially soil
covered with limestone has the largest cleaning efficiency and does not
give unintended side effects. Based on the present tests root zone
installations seem to be effective and they can certainly strengthen
the indoor climate to a great extent.
Résumé
Measurements on installations have shown the following results:
- Health and comfort condition based on questionnaires from
Glostrup Hospital, Denmark showed that health and comfort problems are
in average reduced by 50%.
- Temperature is reduced due to high evapotranspiration from
the soil media and the plants. The temperature reduction is
approximately 3 °C in the range of 2 – 5 °C. The cooling
reduces the relative humidity and evaporation helps raising the
relative humidity.
- PM10* was significant reduced 2-29% in Post-Denmark office and 15% in Transform office comparing with and without air treatment.
- At bank office “Fælleskassen”
(Copenhagen, Denmark) it was observed that the installation could clean
for PM10 relative to the external reference approxemately 75%, and
relative to the internal reference at “Fælleskassen”
50%.
- Chemical reductions tested in climate chambers (Aarhus
University, Denmark) resulted in an efficiency of 90% when comparing
with and without air treatment.
- 22 smell based chemicals are tested between intake and
outlet with cleaning efficiency 80-99% for the chosen chemicals and
25-71% for ammonia.
- Bacteria were reduced with 81-95% when comparing values between intake and discharge from the root zone.
- Micro fungi in the air were reduced by 89% when the soil
was covered with limestone. However the same test, without limestone,
increased the emission of micro fungi by a factor of 3.
- Efficiency based on number of fungal spores/m³ air
showed an 81% reduction after passing through root zone covered with
limestone. However yeast cells from plants can released and raise
concentration nearby the vegetation.
* Particulate matter up to 10 micrometers in size, ”big”
particles between 2.5 and 10 micrometers in smoke, dust and dirt from
factories, roads and farming, as well as mould spores and pollen
Principle root zone air treatment
Authors
Jørgen Løgstrup
Søren Thorhauge Andersen
altered version by Michael Blumberg
Bacess A/S and Transform af 1994 ApS
Postgaardsvej 11
9260 Gistrup, Denmark
Patent: EU 1356239, ZL 01822087.8 (China), 6,638,338 B2 (USA)
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